If you would like to give someone access to one course but not to your whole Intuto site you can do this by following the steps in this article.
A Course Contributor can be added to individual courses through the users page. Just select the User you want to make a Contributor by ticking their name, then selecting Bulk Actions. Then click on Resister _ User into Course/Collection.
When you select Course a new option will appear to register them as a Contributor.
Contact firstname.lastname@example.org for more information